Identifying remote units in a wireless distribution system (WDS) based on assigned unique temporal delay patterns

ABSTRACT

Embodiments of the disclosure relate to identifying remote units in a wireless distribution system (WDS) based on assigned unique temporal delay patterns. The WDS includes a plurality of remote units configured to communicate communications signals in signal paths. Each of the signal paths is assigned a unique temporal delay pattern. The communications signals are digitally delayed by respective delay elements based on the plurality of unique temporal delay patterns to provide delayed communications signals. A remote unit identification system analyzes a delayed communications signal to determine a respective temporal delay pattern associated within the delayed communication signal. By uniquely identifying a remote unit from which a delayed communication signal is communicated, it is possible to determine the locations client devices in the WDS, thus enabling a variety of location-based services and optimizations in the WDS.

PRIORITY APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/281,907, filed Sep. 30, 2016 which claims the benefit of priorityunder 35 U.S.C. §119 of U.S. Provisional Application No. 62/312,130,filed on Mar. 23, 2016, the content of which are relied upon andincorporated herein by reference in their entireties.

BACKGROUND

The disclosure relates generally to a wireless distribution system(WDS), and more particularly to identifying remote units in a WDS.

Wireless customers are increasingly demanding digital data services,such as streaming video and other multimedia contents, for example. Somewireless customers use their wireless devices in areas poorly servicedby conventional cellular networks, such as inside certain buildings orareas. One response to the intersection of these two concerns has beenthe use of WDSs, such as a distributed antenna system (DAS) as anexample. A DAS can be particularly useful when deployed inside buildingsor other indoor environments where client devices may not otherwise beable to effectively receive radio frequency (RF) signals from a basetransceiver station (BTS), for example, of a conventional cellularnetwork. The DAS is configured to provide multiple coverage areas insidethe buildings to support higher capacity and improved RF coverage. Eachcoverage area includes one or more remote units configured to providecommunications services to the client devices within antenna ranges ofthe remote units.

In this regard, FIG. 1 illustrates distribution of communicationsservices to remote coverage areas 100(1)-100(N) of a WDS 102, such as adistributed antenna system (DAS) for example. These communicationsservices can include cellular services, wireless services, such as radiofrequency identification (RFID) tracking, Wireless Fidelity (Wi-Fi),local area network (LAN), wireless LAN (WLAN), worldwideinteroperability for microwave access (WiMAX), wide-band code-divisionmultiple access (WCDMA), long-term evolution (LTE), and combinationsthereof, as examples. The remote coverage areas 100(1)-100(N) may beremotely located. In this regard, the remote coverage areas100(1)-100(N) are created by and centered on remote units 104(1)-104(N)(e.g., remote antenna units) connected to a central unit 106 (e.g., ahead-end controller, a head-end unit, or a head-end equipment). Thecentral unit 106 may be communicatively coupled to a signal source 108,for example, a base transceiver station (BTS) or a baseband unit (BBU).In this regard, the central unit 106 receives downlink communicationssignals 110D from the signal source 108 to be distributed to the remoteunits 104(1)-104(N). The remote units 104(1)-104(N) are configured toreceive the downlink communications signals 110D from the central unit106 over a communications medium 112 to be distributed to the respectiveremote coverage areas 100(1)-100(N) of the remote units 104(1)-104(N).Each of the remote units 104(1)-104(N) may include an RFtransmitter/receiver and a respective antenna 114(1)-114(N) operablyconnected to the RF transmitter/receiver to wirelessly distribute thecommunications services to client devices 116 within the respectiveremote coverage areas 100(1)-100(N). The remote units 104(1)-104(N) arealso configured to receive uplink communications signals 110U from theclient devices 116 in the respective remote coverage areas 100(1)-100(N)to be distributed to the signal source 108.

It may be important to determine the location of client devices 116within the WDS 102. For example, many context-aware and location-awarewireless services, such as enhanced 911 (E911) services, rely onaccurately detecting the locations of wireless communications devices. Asatellite-based location detection system, such as global positioningsystem (GPS) in the United States, may be unreliable in indoorenvironments served by the WDS 102 due to the inherent inability of asatellite signal to penetrate obstacles like building walls. Although itmay be possible to determine general locations of the client devices 116based on a signal source (e.g., base station) in a conventional cellularnetwork, it remains challenging for signal sources to pinpoint thelocations of the client devices within a WDS, such as WDS 102 in FIG. 1,with a higher degree of accuracy. The location of the client device 116may be determined within in the WDS 102 based on identify the locationof the remote unit 104(1)-104(N) with which the client device 116 iscommunicating. However, since the uplink communications signals 110Ufrom the remote units 104(1)-104(N) are combined in the central unit 106before being distributed to the signal source 102, the particular remoteunit 104 with which the client devices 116 are communicating cannot bedetermined.

No admission is made that any reference cited herein constitutes priorart. Applicant expressly reserves the right to challenge the accuracyand pertinency of any cited documents.

SUMMARY

Embodiments of the disclosure relate to identifying remote units in awireless distribution system (WDS) based on assigned unique temporaldelay patterns. For example, identifying remote units in a WDS can beused for determining client device location within the WDS. In thisregard, the WDS includes a plurality of remote units configured tocommunicate communications signals, for example downlink communicationssignals and uplink communications signals, in signal pathscommunicatively coupled to the plurality of remote units. Each of thesignal paths corresponding to a respective remote unit is assigned aunique temporal delay pattern. The communications signals communicatedin the signal paths are digitally delayed by respective delay elementsprovided in the signal paths based on the plurality of unique temporaldelay patterns assigned to the remote units to provide delayedcommunications signals. To identify a remote unit associated with adelayed communications signal, a remote unit identification system isprovided. The remote unit identification system is configured to analyzea delayed communications signal to determine a respective uniquetemporal delay pattern (e.g., a sequence of timing advances (TAs))associated within the delayed communications signal. This allows theremote unit identification system to identify the remote unit among theplurality of remote units that communicates the delayed communicationssignal by associating the analyzed temporal delay pattern in the delayedcommunications signal with the unique temporal delay patterns assignedto the remote units. By uniquely identifying a remote unit with which adelayed communication signal is communicated, it is possible todetermine the locations of client devices in the WDS, thus enabling avariety of location-based services and optimizations in the WDS, asexamples.

One embodiment of the disclosure relates to a remote unit identificationsystem for uniquely identifying a plurality of remote units in a WDS.The remote unit identification system comprises a controller configuredto assign a plurality of unique temporal delay patterns to the pluralityof remote units in the WDS, respectively. Each remote unit among theplurality of remote units is configured to communicate a respectivecommunications signal among a plurality of communications signals with acentral unit in the WDS in a respective signal path among a plurality ofsignal paths disposed between the central unit and the plurality ofremote units. The respective communications signal is digitally delayedby a respective delay element among a plurality of delay elementsdisposed in the respective signal path among the plurality of signalpaths based on a respective unique temporal delay pattern assigned tothe remote unit to provide a respective delayed communications signal.The remote unit identification system also comprises a determinationunit. The determination unit is configured to analyze at least onedelayed communications signal communicated in at least one signal pathamong the plurality of signal paths. The determination unit is alsoconfigured to determine a unique temporal delay pattern associated withthe at least one delayed communications signal. The determination unitis also configured to identify a remote unit among the plurality ofremote units communicating the at least one delayed communicationssignal in the at least one signal path based on the unique temporaldelay pattern.

An additional embodiment of the disclosure relates to a method foruniquely identifying a plurality of remote units in a WDS. The methodcomprises assigning a plurality of unique temporal delay patterns to theplurality of remote units communicatively coupled to a plurality ofsignal paths, respectively. The method also comprises digitally delayinga plurality of communications signals communicated in the plurality ofsignal paths based on the plurality of unique temporal delay patterns toprovide a plurality of delayed communications signals, respectively. Themethod also comprises analyzing the plurality of delayed communicationssignals communicated in the plurality of signal paths. The method alsocomprises determining a unique temporal delay pattern associated witheach of the plurality of delayed communications signals communicated ina respective signal path among the plurality of signal paths. The methodalso comprises identifying a remote unit among the plurality of remoteunits communicatively coupled to the respective signal path based on theunique temporal delay pattern.

An additional embodiment of the disclosure relates to a WDS. The WDScomprises a plurality of signal paths. The WDS also comprises aplurality of remote units. Each remote unit among the plurality ofremote units is communicatively coupled to a respective signal pathamong the plurality of signal paths. The WDS also comprises a centralunit configured to communicate a respective communications signal amonga plurality of communications signals to each remote unit among theplurality of remote units in the respective signal path communicativelycoupled to the remote unit. The WDS also comprises a plurality of delayelements disposed in the plurality of signal paths, respectively. Eachdelay element among the plurality of delay elements is configured todigitally delay the respective communications signal communicated in therespective signal path according to a unique temporal delay patternamong a plurality of unique temporal delay patterns assigned to arespective remote unit among the plurality of remote unitscommunicatively coupled to the respective signal path to provide adelayed communications signal in the respective signal path. The WDSalso comprises a remote unit identification system. The remote unitidentification system comprises a controller configured to assign theplurality of unique temporal delay patterns to the plurality of remoteunits in the WDS. The remote unit identification system also comprises adetermination unit. For at least one delayed communications signalprovided in at least one signal path among the plurality of signalpaths, the determination unit is configured to determine a uniquetemporal delay pattern associated with the at least one delayedcommunications signal. For the at least one delayed communicationssignal provided in the at least one signal path among the plurality ofsignal paths, the determination unit is also configured to identify aremote unit among the plurality of remote units communicatively coupledto the at least one signal path based on the unique temporal delaypattern.

An additional embodiment of the disclosure relates to a method foridentifying a client device in a WDS. The method comprises receiving anidentification of the client device. The method also comprises logicallyorganizing a plurality of remote units in the WDS into a first remoteunit group and a second remote unit group. For each remote unit groupamong the first remote unit group and the second remote unit group, themethod comprises assigning one or more unique temporal delay patterns toone or more remote units in the remote unit group, respectively. Foreach remote unit group among the first remote unit group and the secondremote unit group, the method also comprises delaying one or morecommunications signals communicated with the one or more remote units inthe remote unit group based on the one or more unique temporal delaypatterns, respectively. For each remote unit group among the firstremote unit group and the second remote unit group, the method alsocomprises analyzing a call report to determine whether a timing advance(TA) corresponding to the client device changes in response to delayingthe one or more communications signals based on the one or more uniquetemporal delay patterns. For each remote unit group among the firstremote unit group and the second remote unit group, if the TA of theclient device has changed and if the remote unit group comprises onlyone remote unit, the method also comprises reporting an identificationof the remote unit in the remote unit group. For each remote unit groupamong the first remote unit group and the second remote unit group, ifthe TA of the client device has changed and if the remote unit groupcomprises more than one remote unit, the method also comprises logicallyorganizing the remote units in the remote unit group into the firstremote unit group and the second remote unit group.

Additional features and advantages will be set forth in the detaileddescription which follows and, in part, will be readily apparent tothose skilled in the art from the description or recognized bypracticing the embodiments as described in the written description andclaims hereof, as well as the appended drawings.

It is to be understood that both the foregoing general description andthe following detailed description are merely exemplary and are intendedto provide an overview or framework to understand the nature andcharacter of the claims.

The accompanying drawings are included to provide a furtherunderstanding of the disclosure, and are incorporated in and constitutea part of this specification. The drawings illustrate one or moreembodiment(s), and together with the description serve to explainprinciples and operation of the various embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of an exemplary wireless distributionsystem (WDS);

FIG. 2 is a schematic diagram of an exemplary WDS that includes a remoteunit identification system configured to uniquely identify a pluralityof remote units in the WDS by associating temporal delay patterns indelayed communications signals with unique temporal delay patternsassociated with the remote units;

FIG. 3 is a schematic diagram providing an exemplary illustration of theplurality of unique temporal delay patterns in FIG. 2, which may bedefined as a sequence of timing advances (TAs) as defined in the thirdgeneration partnership project (3GPP) long-term evolution (LTE)specification, to uniquely identify the plurality of remote units;

FIG. 4 is a flowchart of an exemplary remote unit identification processthat may be employed to uniquely identify the plurality of remote unitsin the WDS of FIG. 2 by associating temporal delay patterns in delayedcommunication signals with unique temporal delay patterns associatedwith the remote units;

FIG. 5A is a table providing an exemplary illustration of the pluralityof unique temporal delay patterns of FIG. 2, each defined based onrespective timing advance (TA) changes;

FIG. 5B is a table providing an exemplary illustration of determiningthe plurality of unique temporal delay patterns based on propagationdelays of a plurality of delayed communications signals in the WDS ofFIG. 2;

FIG. 6 is a schematic diagram of an exemplary WDS configured to uniquelyidentify at least one remote unit among the plurality of remote units ofFIG. 2 communicating in a specific radio frequency (RF) band based on atleast one unique temporal delay pattern assigned to the RF band;

FIG. 7 is a flowchart of an exemplary client device location process foridentifying a client device relative to a remote unit in the WDSs ofFIGS. 2 and 6 based on an identification of the client device;

FIG. 8 is a schematic diagram of an exemplary WDS that can be configuredto function as the WDSs of FIGS. 2 and 6;

FIG. 9 is a partial schematic cut-away diagram of an exemplary buildinginfrastructure in which the WDSs of FIGS. 2 and 6 can be employed; and

FIG. 10 is a schematic diagram of a generalized representation of anexemplary controller that can be included in the WDSs of FIGS. 2 and 6to identify the plurality of remote units in the WDSs of FIGS. 2 and 6,wherein an exemplary computer system is adapted to execute instructionsfrom an exemplary computer-readable medium.

DETAILED DESCRIPTION

Embodiments of the disclosure relate to identifying remote units in awireless distribution system (WDS) based on assigned unique temporaldelay patterns. For example, identifying remote units in a WDS can beused for determining client device location within the WDS. In thisregard, the WDS includes a plurality of remote units configured tocommunicate communications signals, for example downlink communicationssignals and uplink communications signals, in signal pathscommunicatively coupled to the plurality of remote units. Each of thesignal paths corresponding to a respective remote unit is assigned aunique temporal delay pattern. The communications signals communicatedin the signal paths are digitally delayed by respective delay elementsprovided in the signal paths based on the plurality of unique temporaldelay patterns assigned to the remote units to provide delayedcommunications signals. To identify a remote unit associated with adelayed communications signal, a remote unit identification system isprovided. The remote unit identification system is configured to analyzea delayed communications signal to determine a respective uniquetemporal delay pattern (e.g., a sequence of timing advances (TAs))associated within the delayed communications signal. This allows theremote unit identification system to identify the remote unit among theplurality of remote units that communicates the delayed communicationssignal by associating the analyzed temporal delay pattern in the delayedcommunications signal with the unique temporal delay patterns assignedto the remote units. By uniquely identifying a remote unit with which adelayed communication signal is communicated, it is possible todetermine the locations of client devices in the WDS, thus enabling avariety of location-based services and optimizations in the WDS, asexamples.

In this regard, FIG. 2 is a schematic diagram of an exemplary WDS 200that includes a remote unit identification system 202 configured touniquely identify a plurality of remote units 204(1)-204(N) byassociating a plurality of unique temporal delay patterns 206(1)-206(N)with the plurality of remote units 204(1)-204(N), respectively. Withreference to FIG. 2, the WDS 200 includes a central unit 208. The WDS200 also includes a plurality of signal paths 210(1)-210(N) disposedbetween the central unit 208 and the plurality of remote units204(1)-204(N). In this regard, the plurality of signal paths210(1)-210(N) communicatively couples the plurality of remote units204(1)-204(N) with the central unit 208. The central unit 208communicates a plurality of communications signals 212(1)-212(N) withthe plurality of remote units 204(1)-204(N) in the plurality of signalpaths 210(1)-210(N), respectively.

The remote unit identification system 202 includes a controller 214 anda determination unit 216. In non-limiting examples, the determinationunit 216 may be provided as an electronic circuitry, a general purposeprocessor, a dedicated signal processor, and/or an electronic device.The WDS 200 also includes a plurality of delay elements 218(1)-218(N)provided in the plurality of signal paths 210(1)-210(N), respectively.In this regard, each of the plurality of remote units 204(1)-204(N) isassociated with a respective delay element among the plurality of delayelements 218(1)-218(N) in a respective signal path among the pluralityof signal paths 210(1)-210(N). In a first non-limiting example, theplurality of delay elements 218(1)-218(N) may be provided in theplurality of remote units 204(1)-204(N). In a second non-limitingexample, it is also possible to provide the plurality of delay elements218(1)-218(N) in the central unit 208.

The controller 214 assigns the plurality of unique temporal delaypatterns 206(1)-206(N) to the plurality of remote units 204(1)-204(N),respectively. In a non-limiting example, the controller 214 may storethe plurality of unique temporal delay patterns 206(1)-206(N) in localmemory or in memories in the plurality of delay elements 218(1)-218(N).The controller 214 may configure and/or control the plurality of delayelements 218(1)-218(N) to digitally delay the plurality ofcommunications signals 212(1)-212(N) based on the plurality of uniquetemporal delay patterns 206(1)-206(N), respectively, to provide aplurality of delayed communications signals 212′(1)-212′(N). In anon-limiting example, the controller 214 may configure and/or controlthe plurality of delay elements 218(1)-218(N) via at least one controlsignal 220. The plurality of delayed communications signals212′(1)-212′(N) is the same as the plurality of communications signals212(1)-212(N), but is temporally delayed by the plurality of delayelements 218(1)-218(N) according to the plurality of unique temporaldelay patterns 206(1)-206(N).

With continuing reference to FIG. 2, the determination unit 216 isconfigured to analyze at least one delayed communications signal amongthe plurality of delayed communications signals 212′(1)-212′(N)communicated in at least one signal path among the plurality of signalpaths 210(1)-210(N) to determine a unique temporal delay patternassociated with the at least one delayed communications signal. Thedetermination unit 216 can then uniquely identify a remote unit amongthe plurality of remote units 204(1)-204(N) communicating the at leastone delayed communications signal in the at least one signal path basedon the determined unique temporal delay pattern. In this regard, byanalyzing the plurality of delayed communications signals212′(1)-212′(N) communicated in the plurality of signal paths210(1)-210(N) to determine the plurality of unique temporal delaypatterns 206(1)-206(N), the determination unit 216 is able to uniquelyidentify the plurality of remote units 204(1)-204(N) based on theplurality of determined unique temporal delay patterns 206(1)-206(N),respectively. By uniquely identifying the plurality of remote units204(1)-204(N) based on the plurality of unique temporal delay patterns206(1)-206(N), it is possible to determine locations of the plurality ofremote units 204(1)-204(N), thus enabling a variety of location-basedservices and optimizations in the WDS 200. In a non-limiting example,each of the plurality of remote units 204(1)-204(N) may correspond to apredefined physical location (e.g., conference room A of building C,second floor of building G, etc.). The predefined physical location maybe predefined in association with identification (e.g., remote unitname) of the remote unit. In this regard, the determination unit 216 maydetermine the predefined physical location of each of the plurality ofremote units 204(1)-204(N) based the identification of the remote unit.

To explain one way that the determination unit 216 can uniquely identifythe plurality of remote units 204(1)-204(N) based on the plurality ofunique temporal delay patterns 206(1)-206(N), FIG. 3 is provided. FIG. 3is a schematic diagram providing an exemplary illustration of theplurality of unique temporal delay patterns 206(1)-206(N) in FIG. 2 thatcan uniquely identify the plurality of remote units 204(1)-204(N). Withreference to FIG. 3, the plurality of unique temporal delay patterns206(1)-206(N) is assigned to the plurality of remote units204(1)-204(N), respectively. Each of the plurality of unique temporaldelay patterns 206(1)-206(N) includes a plurality of temporal delayperiods 300(1)-300(3). Although each of the plurality of unique temporaldelay patterns 206(1)-206(N) is shown hereinafter to include only threerespective temporal delay periods 300(1)-300(3), it shall be appreciatedthat any integer number of temporal delay periods may be included ineach of the plurality of unique temporal delay patterns 206(1)-206(N),as long as the integer number is greater than one and reasonable.Accordingly, the plurality of unique temporal delay patterns206(1)-206(N) includes a plurality of temporal delay periods302(1,1)-302(N,3), respectively. For example, the unique temporal delaypattern 206(1) includes the plurality of temporal delay periods302(1,1)-302(1,3), the unique temporal delay pattern 206(2) includes theplurality of temporal delay periods 302(2,1)-302(2,3), and so on. In anon-limiting example, each of the plurality of temporal delay periods302(1,1)-302(N,3) has a duration of one second (s).

With continuing reference to FIG. 3, each of the plurality of temporaldelay periods 302(N,1)-302(N,3) corresponds to a respective temporaldelay value (Δ Delay). The A Delay may be defined as integer multiple ofa predefined temporal unit (TU). In a non-limiting example, the TU mayequal to two hundred sixty point four (260.4) nanoseconds (ns) incommunications systems, such as LTE for example. The three A Delayscorresponding to the temporal delay periods 300(1)-300(3) in each of theplurality of unique temporal delay patterns 206(1)-206(N) define threetemporal delays to be injected into each of the plurality ofcommunications signals 212(1)-212(N) during the temporal delay periods300(1)-300(3). Hence, in the non-limiting example, each of the pluralityof unique temporal delay patterns 206(1)-206(N) is defined by a sequenceof the three A Delays. In this regard, in another non-limiting example,the controller 214 may control each of the plurality of delay elements218(1)-218(N) to digitally delay a respective communications signalaccording to the three A Delays in the temporal delay periods300(1)-300(3), respectively, thus generating a respective uniquetemporal delay pattern in a respective delayed communications signal.For convenience of discussion and illustration, the unique temporaldelay patterns 206(1), 206(2), and 206(N) are discussed hereinafter asnon-limiting examples.

For example, the three A Delays corresponding to the temporal delayperiods 300(1)-300(3) of the unique temporal delay pattern 206(1) arezero (0) TU, two (2) TU, and four (4) TU, respectively in this example.In this regard, the delay element 218(1) is configured to digitallydelay the communications signal 212(1) communicated on the signal path210(1) by 0 TU, 2 TU, and 4 TU during the temporal delay periods300(1)-300(3), respectively. In a non-limiting example, the delayelement 218(1) may digitally delay the communications signal 212(1) bybuffering the communications signal 212(1) for 0 TU, 2 TU, and 4 TUduring the temporal delay periods 300(1)-300(3), respectively. As such,the unique temporal delay pattern 206(1), as defined by a combination ofthe three A Delays during the temporal delay periods 300(1)-300(3), is a0TU-2TU-4TU temporal delay pattern that will be associated with thedelayed communications signal 212′(1) as well. In this regard, if thedetermination unit 216 determines that a delayed communications signalamong the plurality of delayed communications signals 212′(1)-212′(N) isassociated with the 0TU-2TU-4TU temporal delay pattern, thedetermination unit 216 may be able to identify the remote unit 204(1) asthe remote unit communicating the delayed communications signal. In thisregard, the determination unit 216 may determine a remote unit among theplurality of remote units 204(1)-204(N) by correlating a sequence of ADelays in time in a delayed communications signal among the plurality ofdelayed communications signals 212′(1)-212′(N) with a respective uniquetemporal delay pattern associated with the remote unit that communicatesthe delayed communications signal.

However, for the determination unit 216 to definitively identify theremote unit 204(1) based on the 0TU-2TU-4TU temporal delay pattern, the0TU-2TU-4TU temporal delay pattern is configured to be uniquelydistinguishable from rest of the plurality of unique temporal delaypatterns 206(1)-206(N). As illustrated in FIG. 3, for example, theunique temporal delay pattern 206(2), as defined by a combination of thethree A Delays during the temporal delay periods 300(1)-300(3), is a4TU-0TU-2TU temporal delay pattern that is uniquely distinguishable fromthe 0TU-2TU-4TU temporal delay pattern of the unique temporal delaypattern 206(1). In a non-limiting example, the three A Delays during thetemporal delay periods 300(1)-300(3) are applied to the remote units204(1)-204(N) substantially concurrently. Accordingly, respectivetemporal delay periods corresponding to the 4TU-0TU-2TU and the0TU-2TU-4TU start and finish at substantially similar times among theremote units 204(1)-204(N). Likewise, the unique temporal delay pattern206(N), as defined by a combination of the three A Delays during thetemporal delay periods 300(1)-300(3), is a 0TU-2TU-2TU temporal delaypattern, that is uniquely distinguishable from the 0TU-2TU-4TU temporaldelay pattern of the unique temporal delay pattern 206(1) and the4TU-0TU-2TU temporal delay pattern of the unique temporal delay pattern206(2). As such, each of the plurality of unique temporal delay patterns206(1)-206(N) can be defined to be uniquely distinguishable from rest ofthe plurality of unique temporal delay patterns 206(1)-206(N). As aresult, the plurality of remote units 204(1)-204(N) can be uniquelyidentified based on the plurality of unique temporal delay patterns206(1)-206(N) exhibited in the plurality of delayed communicationssignals 212′(1)-212′(N).

With reference back to FIG. 2, the plurality of signal paths210(1)-210(N) further includes a plurality of downlink signal paths210D(1)-210D(N) and a plurality of uplink signal paths 210U(1)-210U(N),respectively. In this regard, the plurality of remote units204(1)-204(N) is communicatively coupled to the central unit 208 via theplurality of downlink signal paths 210D(1)-210D(N) and the plurality ofuplink signal paths 210U(1)-210U(N). Accordingly, the central unit 208can communicate a plurality of downlink communications signals212D(1)-212D(N) to the plurality of remote units 204(1)-204(N) in theplurality of downlink signal paths 210D(1)-210D(N) and receive aplurality of uplink communications signals 212U(1)-212U(N) from theplurality of remote units 204(1)-204(N) in the plurality of uplinksignal paths 210U(1)-210U(N), respectively. The controller 214 mayconfigure and/or control the plurality of delay elements 218(1)-218(N)to digitally delay the plurality of uplink communications signals212U(1)-212U(N) based on the plurality of unique temporal delay patterns206(1)-206(N), respectively, to provide a plurality of delayed uplinkcommunications signals 212U′(1)-212U′(N).

In one non-limiting example, the controller 214 may configure and/orcontrol the plurality of delay elements 218(1)-218(N) to digitally delaythe plurality of downlink communications signals 212D(1)-212D(N) basedon the plurality of unique temporal delay patterns 206(1)-206(N),respectively, to provide a plurality of delayed downlink communicationssignals 212D′(1)-212D′(N). In another non-limiting example, thecontroller 214 may configure and/or control the plurality of delayelements 218(1)-218(N) to digitally delay the plurality of downlinkcommunications signals 212D(1)-212D(N) and the plurality of uplinkcommunications signals 212U(1)-212U(N) based on the plurality of uniquetemporal delay patterns 206(1)-206(N), respectively, to provide theplurality of delayed downlink communications signals 212D′(1)-212D′(N)and the plurality of delayed uplink communications signals212U′(1)-212U′(N). In this regard, according to the discussions earlier,the plurality of delayed uplink communications signals 212U′(1)-212U′(N)and the plurality of delayed downlink communications signals212D′(1)-212D′(N) are both associated with the plurality of uniquetemporal delay patterns 206(1)-206(N). The determination unit 216 cananalyze at least one of the plurality of delayed uplink communicationssignals 212U′(1)-212U′(N) and/or at least one of the plurality ofdelayed downlink communications signals 212D′(1)-212D′(N). Accordingly,the determination unit 216 can uniquely identify the plurality of remoteunits 204(1)-204(N) based on the plurality of unique temporal delaypatterns 206(1)-206(N) in the plurality of delayed uplink communicationssignals 212U′(1)-212U′(N) and/or the plurality of delayed downlinkcommunications signals 212D′(1)-212D′(N).

FIG. 4 is a flowchart of an exemplary remote unit identification process400 that may be employed to uniquely identify the plurality of remoteunits 204(1)-204(N) in the WDS 200 of FIG. 2. With reference to FIG. 4,the controller 214 assigns the plurality of unique temporal delaypatterns 206(1)-206(N) to the plurality of remote units 204(1)-204(N)that is communicatively coupled to the plurality of signal paths210(1)-210(N), respectively (block 402). The plurality of delay elements218(1)-218(N) digitally delays the plurality of communications signals212(1)-212(N) communicated in the plurality of signal paths210(1)-210(N) based on the plurality of unique temporal delay patterns206(1)-206(N) to provide the plurality of delayed communications signals212′(1)-212′(N), respectively (block 404). Specifically, the pluralityof delay elements 218(1)-218(N) may digitally delay the plurality ofdownlink communications signals 212D(1)-212D(N) communicated in theplurality of downlink signal paths 210D(1)-210D(N) based on theplurality of unique temporal delay patterns 206(1)-206(N) to provide theplurality of delayed downlink communications signals 212D′(1)-212D′(N),respectively. The plurality of delay elements 218(1)-218(N) may alsodigitally delay the plurality of uplink communications signals212U(1)-212U(N) communicated in the plurality of uplink signal paths210U(1)-210U(N) based on the plurality of unique temporal delay patterns206(1)-206(N) to provide the plurality of delayed uplink communicationssignals 212U′(1)-212U′(N), respectively. The plurality of delay elements218(1)-218(N) may also digitally delay the plurality of downlinkcommunications signals 212D(1)-212D(N) communicated in the plurality ofdownlink signal paths 210D(1)-210D(N) and the plurality of uplinkcommunications signals 212U(1)-212U(N) communicated in the plurality ofuplink signal paths 210U(1)-210U(N) based on the plurality of uniquetemporal delay patterns 206(1)-206(N) to provide the plurality ofdelayed downlink communications signals 212D′(1)-212D′(N) and theplurality of delayed uplink communications signals 212U′(1)-212U′(N),respectively. The determination unit 216 also analyzes the plurality ofdelayed communications signals 212′(1)-212′(N) communicated in theplurality of signal paths 210(1)-210(N) (block 406). Specifically, thedetermination unit 216 may analyze the plurality of delayed downlinkcommunications signals 212D′(1)-212D′(N) communicated in the pluralityof downlink signal paths 210D(1)-210D(N) and/or the plurality of delayeduplink communications signals 212U′(1)-212U′(N) communicated in theplurality of uplink signal paths 210U(1)-210U(N). Subsequently, thedetermination unit 216 determines a unique temporal delay patternassociated with each of the plurality of delayed communications signals212′(1)-212′(N) communicated in a respective signal path among theplurality of signal paths 210(1)-210(N) (block 408). Specifically, thedetermination unit 216 may determine the unique temporal delay patternassociated with each of the plurality of delayed downlink communicationssignals 212D′(1)-212D′(N) communicated in a respective downlink signalpath among the plurality of downlink signal paths 210D(1)-210D(N) and/orthe unique temporal delay pattern associated with each of the pluralityof delayed uplink communications signals 212U′(1)-212U′(N) communicatedin a respective uplink signal path among the plurality of uplink signalpaths 210U(1)-210U(N). The determination unit 216 can then identify aremote unit among the plurality of remote units 204(1)-204(N)communicatively coupled to the respective signal path based on theunique temporal delay pattern (block 410). The determination unit 216may also identify the remote unit among the plurality of remote units204(1)-204(N) communicatively coupled to the respective downlink signalpath and/or the respective uplink signal path based on the uniquetemporal delay pattern.

With reference back to FIG. 2, the central unit 208 is communicativelycoupled to one or more signal sources 222(1)-222(M) (e.g., BTS,evolution node B (eNB), etc.). The central unit 208 is configured tocommunicate one or more RF communications signals 224(1)-224(M) with theone or more signal sources 222(1)-222(M), respectively. Morespecifically, the central unit 208 is configured to receive one or moredownlink RF communications signals 224D(1)-224D(M) from the one or moresignal sources 222(1)-222(M) and communicate the one or more downlink RFcommunications signals 224D(1)-224D(M) to the plurality of remote units204(1)-204(N) as the plurality of downlink communications signals212D(1)-212D(N). The central unit 208 is also configured to communicatethe plurality of uplink communications signals 212U(1)-212U(N) receivedfrom the plurality of remote units 204(1)-204(N) as one or more uplinkRF communications signals 224U(1)-224U(M) to the one or more signalsources 222(1)-222(M).

With continuing reference to FIG. 2, each of the plurality of remoteunits 204(1)-204(N) communicates a respective communications signalamong the plurality of communications signals 212(1)-212(N) to arespective client device 226. More specifically, each of the pluralityof remote units 204(1)-204(N) transmits a respective downlinkcommunications signal among the plurality of downlink communicationssignals 212D(1)-212D(N) to the respective client device 226 and receivesa respective uplink communications signal among the plurality of uplinkcommunications signals 212U(1)-212U(N) from the respective client device226. Although only one respective client device 226 is shown in FIG. 2for each of the plurality of remote units 204(1)-204(N), it shall beappreciated that each of the plurality of remote units 204(1)-204(N) cancommunicate concurrently with more than one respective client device226.

In a non-limiting example, in wireless communications systems such asLTE, each of the client devices 226, for example the client device 226associated with the remote unit 204(1), is assigned a respective TA by arespective signal source among the one or more signal sources222(1)-222(M). The respective TA assigned to the client device 226 is amedium access control (MAC) control element (CE) that the respectivesignal source uses to control transmission timing of a respectivecommunications signal among the plurality of communications signals212(1)-212(N) communicated with the client device 226 to achieve timingsynchronization with a subframe timing determined by the respectivesignal source. In a non-limiting example, the respective signal sourcekeeps measuring the timing difference between the subframe timing anduplink control signals, such as sounding reference signals (SRSs),received from the client devices 226 on uplink control channels (e.g.,physical uplink shared channel (PUSCH) or physical uplink controlchannel (PUCCH)). Based on the measured timing difference, therespective signal source can determine a round-trip propagation delaybetween the respective signal source and the client device 226. Based onthe determined round-trip propagation delay, the respective signalsource can assign the respective TA to the client device 226 toaccommodate for respective propagation delay between the client device226 and the respective signal source. In this regard, the respective TAassigned to the client device 226 accounts for one-half of thedetermined round-trip propagation delay. The respective TA assigned toeach of the client devices 226 is defined as an integer multiple of theTU, which may equal 260.4 ns in LTE, as previously described.

With continuing reference to FIG. 2, as discussed above, the respectiveTA assigned to each of the client devices 226 reflects the respectivepropagation delay between each of the client devices 226 and therespective signal source among the one or more signal sources222(1)-222(M). The respective propagation delay associated with each ofthe plurality of communications signals 212(1)-212(N) communicated withthe client devices 226 may be obtained from a call report 228, which maycontain information as shown in Table 1 below as a non-limiting example.In a non-limiting example, the determination unit 216 may retrieve thecall report 228 from a network management system (NMS) 230.

TABLE 1 Time (s) Client Device Identification Related Parameters00.06.05 Client device 226 associated TA = 23TU, . . . with the remoteunit 204(1) 00.06.05 Client device 226 associated TA = 17TU, . . . withthe remote unit 204(2) : : 00.06.05 Client device 226 associated TA =24TU, . . . with the remote unit 204(N) 00.06.06 Client device 226associated TA = 25TU, . . . with the remote unit 204(1) 00.06.06 Clientdevice 226 associated TA = 13TU, . . . with the remote unit 204(2) : :00.06.06 Client device 226 associated TA = 26TU, . . . with the remoteunit 204(N) 00.06.07 Client device 226 associated TA = 27TU, . . . withthe remote unit 204(1) 00.06.07 Client device 226 associated TA = 15TU,. . . with the remote unit 204(2) : : 00.06.07 Client device 226associated TA = 26TU, . . . with the remote unit 204(N)

As shown in Table 1, at time 00.06.05 corresponding to the temporaldelay period 300(1) of FIG. 3, the propagation delay of thecommunications signals 212(1), 212(2), and 212(N) are 23TU, 17TU, and24TU, respectively. The 23TU, 17TU, and 24TU propagation delays may beobserved in the downlink communications signals 212D(1), 212D(2), and212D(N) and/or the uplink communications signals 212U(1), 212U(2), and212U(N), respectively. Likewise, at time 00.06.06 corresponding to thetemporal delay period 300(2) of FIG. 3, the propagation delay of thecommunications signals 212(1), 212(2), and 212(N) are 25TU, 13TU, and26TU, respectively. The 25TU, 13TU, and 26TU propagation delays may alsobe observed in the downlink communications signals 212D(1), 212D(2), and212D(N) and/or the uplink communications signals 212U(1), 212U(2), and212U(N), respectively. At time 00.06.07 corresponding to the temporaldelay period 300(3) of FIG. 3, the propagation delay of thecommunications signals 212(1), 212(2), and 212(N) are 27TU, 15TU, and26TU, respectively. The 27TU, 15TU, and 26TU propagation delays may alsobe observed in the downlink communications signals 212D(1), 212D(2), and212D(N) and/or the uplink communications signals 212U(1), 212U(2), and212U(N), respectively. In this regard, the propagation delay of thecommunications signal 212(1) communicated with the client device 226 viathe remote unit 204(1) has a respective propagation delay pattern of23TU-25TU-27TU during the temporal delay periods 300(1)-301(3). Thevariations in the propagation delay may be the result of temporal delaysinjected into the downlink communications signal 212D(1) and/or theuplink communications signal 212U(1) by the delay element 218(1).Similarly, the propagation delay of the communications signal 212(2)communicated with the client device 226 via the remote unit 204(2) has arespective propagation delay pattern of 17TU-13TU-15TU during thetemporal delay periods 300(1)-301(3). The propagation delay of thecommunications signal 212(N) communicated with the client device 226 viathe remote unit 204(N) has a respective propagation delay pattern of24TU-26TU-26TU during the temporal delay periods 300(1)-301(3).Likewise, the variations in the propagation delay may be the result oftemporal delays injected into the downlink communications signals212D(2) and 212D(N) and/or the uplink communications signals 212U(2) and212U(N) by the delay elements 218(2) and 218(N), respectively.

According to previous discussions in FIG. 3, each of the plurality ofunique temporal delay patterns 206(1)-206(N) is defined by a combinationof three A Delays corresponding to respective temporal delay periods300(1)-300(3). As such, if the respective TAs assigned to the clientdevices 226 are known, it may be possible to determine the plurality ofunique temporal delay patterns 206(1)-206(N) based on the propagationdelay patterns associated with the plurality of delayed communicationssignals 212′(1)-212′(N). In this regard, FIG. 5A is a table 500providing an exemplary illustration of the plurality of unique temporaldelay patterns 206(1)-206(N) of FIG. 2, each defined based on respectiveTA changes in the three temporal delay periods 300(1)-300(3) of FIG. 3.Common elements between FIGS. 2, 3, and 5A are shown therein with commonelement numbers and will not be re-described herein.

With reference to FIG. 5A, the plurality of unique temporal delaypatterns 206(1)-206(N) is defined in one or more intervals502(1)-502(3). Although only three intervals 502(1)-502(3) are shown inFIG. 5A, it shall be appreciated that any integer number of intervalsmay be defined for the plurality of unique temporal delay patterns206(1)-206(N). Each of the one or more intervals 502(1)-502(3) includesthe three temporal delay periods 300(1)-300(3). Each of the threetemporal delay periods 300(1)-300(3) corresponds to a respective TAchange (ATA) that is expressed as integer multiple of TU. In anon-limiting example, the TU may equal 260.4 ns, as previouslydescribed.

The three ATUs corresponding to the temporal delay periods 300(1)-300(3)in each of the plurality of unique temporal delay patterns 206(1)-206(N)define three temporal delays to be injected into each of the pluralityof communications signals 212(1)-212(N) during the temporal delayperiods 300(1)-300(3). For example, the three ATUs corresponding to thetemporal delay periods 300(1)-300(3) of the unique temporal delaypattern 206(1) are 0TU, 2TU, and 4TU, respectively. Similarly, the threeATUs corresponding to the temporal delay periods 300(1)-300(3) of theunique temporal delay pattern 206(2) are 4TU, 0TU, and 2TU,respectively. Likewise, the three ATUs corresponding to the temporaldelay periods 300(1)-300(3) of the unique temporal delay pattern 206(N)are 0TU, 2TU, and 2TU, respectively. In a non-limiting example, theplurality of unique temporal delay patterns 206(1)-206(N) may berepeated in the one or more intervals 502(1)-502(3) for improvedreliability.

FIG. 5B is a table 504 providing an exemplary illustration ofdetermining the plurality of unique temporal delay patterns206(1)-206(N) of FIG. 2 based on propagation delays of the plurality ofdelayed communications signals 212′(1)-212′(N). Common elements betweenFIGS. 2, 3, 5A, and 5B are shown therein with common element numbers andwill not be re-described herein. For the convenience of illustration,FIG. 5B is discussed herein with reference to the plurality of delayeduplink communications signals 212U′(1)-212U′(N). It shall be appreciatedthat the working principles discussed herein can be applied to theplurality of delayed downlink communications signals 212D′(1)-212D′(N)as well. The table 504 includes a first column 506, a second column 508,a third column 510, a fourth column 512, and a fifth column 514. Thetable 504 also includes a plurality of rows 516(1)-516(N) correspondingrespectively to the plurality of remote units 204(1)-204(N) and theplurality of unique temporal delay patterns 206(1)-206(N). The rows516(1), 516(2), and 516(N) are discussed herein as non-limitingexamples.

With reference to FIG. 5B, the first column 506 indicates that the rows516(1), 516(2), and 516(N) correspond respectively to the client devices226 associated with the remote units 204(1), 204(2), and 204(N),respectively. The second column 508 indicates that the client devices226 associated with the remote units 204(1), 204(2), and 204(N) areassigned respective TAs of 23TU, 13TU, and 24TU, respectively. The thirdcolumn 510 indicates the uplink propagation delays of the delayed uplinkcommunications signals 212U′(1), 212U′(2), and 212U′(N) during the threetemporal delay periods 300(1)-300(3). The third column 510 in row 516(1)indicates that the delayed uplink communications signal 212U′(1) hasuplink respective propagation delays of 23TU, 25TU, and 27TU during thethree temporal delay periods 300(1)-300(3), respectively. By subtractingthe respective TA of 23TU from each of the respective uplink propagationdelays of 23TU, 25TU, and 27TU, the fourth column 512 in row 516(1)indicates that the ATAs during the three temporal delay periods300(1)-300(3) are 0TU, 2TU, and 4TU, respectively. As shown in table500, the ATAs of 0TU, 2TU, and 4TU correspond to the unique temporaldelay pattern 206(1), which is assigned to the remote unit 204(1) asindicated by the fifth column 514. Hence, the remote unit 204(1) can beidentified based on the unique temporal delay pattern 206(1) associatedwith the delayed uplink communications signal 212U′(1). As previouslydiscussed in FIG. 2, the determination unit 216 may determine thepredefined physical location of each of the plurality of remote units204(1)-204(N) based the identification of the remote unit. As such, thepredefined physical location of the remote unit 204(1) can bedetermined. Furthermore, in a non-limiting example, it is also possibleto locate the client device 226 associated with the remote unit 204(1)based on the predefined physical location of the remote unit 204(1).

With continuing reference to FIG. 5B, the third column 510 in row 516(2)indicates that the delayed uplink communications signal 212U′(2) hasrespective uplink propagation delays of 17TU, 13TU, and 15TU during thethree temporal delay periods 300(1)-300(3), respectively. By subtractingthe respective TA of 13TU from each of the respective uplink propagationdelays of 17TU, 13TU, and 15TU, the fourth column 512 in row 516(2)indicates that the ATAs during the three temporal delay periods300(1)-300(3) are 4TU, 0TU, and 2TU, respectively. As shown in table500, the ATAs of 4TU, 0TU, and 2TU correspond to the unique temporaldelay pattern 206(2), which is assigned to the remote unit 204(2) asindicated by the fifth column 514. Hence, the remote unit 204(2) can beidentified based on the unique temporal delay pattern 206(2) associatedwith the delayed uplink communications signal 212U′(2). Furthermore, inanother non-limiting example, it is also possible to locate the clientdevice 226 associated with the remote unit 204(2) based on thepredefined physical location of the remote unit 204(2).

With continuing reference to FIG. 5B, the third column 510 in row 516(N)indicates that the delayed uplink communications signal 212U′(N) hasrespective uplink propagation delays of 24TU, 26TU, and 26TU during thethree temporal delay periods 300(1)-300(3), respectively. By subtractingthe respective TA of 24TU from each of the respective uplink propagationdelays of 24TU, 26TU, and 26TU, the fourth column 512 in row 516(N)indicates that the ATAs during the three temporal delay periods300(1)-300(3) are 0TU, 2TU, and 2TU, respectively. As shown in table500, the ATAs of 0TU, 2TU, and 2TU correspond to the unique temporaldelay pattern 206(N), which is assigned to the remote unit 204(N) asindicated by the fifth column 514. Hence, the remote unit 204(N) can beidentified based on the unique temporal delay pattern 206(N) associatedwith the delayed uplink communications signal 212U′(N). Furthermore, inanother non-limiting example, it is also possible to locate the clientdevice 226 associated with the remote unit 204(N) based on thepredefined physical location of the remote unit 204(N).

With reference back to FIG. 2, the one or more downlink RFcommunications signals 224D(1)-224D(M) and the one or more uplink RFcommunications signals 224U(1)-224U(M) may be communicated with the oneor more signal sources 222(1)-222(M) on different RF bands and/orchannels. In some aspects, it may be desired to identify at least oneremote unit among the plurality of remote units 204(1)-204(N) thatcommunicates in a specific RF band and/or channel. In this regard, FIG.6 is a schematic diagram of an exemplary WDS 600 configured to uniquelyidentify at least one remote unit among the plurality of remote units204(1)-204(N) of FIG. 2 communicating in a specific RF band based on atleast one unique temporal delay pattern assigned to an RF band. Commonelements between FIGS. 2 and 6 are shown therein with common elementnumbers and will not be re-described herein.

With reference to FIG. 6, the one or more signal sources 222(1)-222(M)may communicate the one or more downlink RF communications signals224D(1)-224D(M) and the one or more uplink RF communications signals224U(1)-224U(M) in one or more RF bands 602(1)-602(M), respectively. Theone or more signal sources 222(1)-222(M) may also communicate the one ormore downlink RF communications signals 224D(1)-224D(M) and the one ormore uplink RF communications signals 224U(1)-224U(M) in one or more RFchannels 604(1)-604(M), respectively. For example, the signal source222(1) communicates the downlink RF communications signal 224D(1) andthe uplink RF communications signal 224U(1) with the central unit 208 onthe RF band 602(1) or the RF channel 604(1). The signal source 222(2)communicates the downlink RF communications signal 224D(2) and theuplink RF communications signal 224U(2) with the central unit 208 on theRF band 602(2) or the RF channel 604(2). The signal source 222(M)communicates the downlink RF communications signal 224D(M) and theuplink RF communications signal 224U(M) with the central unit 208 on theRF band 602(M) or the RF channel 604(M). The central unit 208communicates the one or more downlink RF communications signals224D(1)-224D(M) to the plurality of remote units 204(1)-204(N) as theplurality of downlink communications signals 212D(1)-212D(N). Thecentral unit 208 also provides the plurality of uplink communicationssignals 212U(1)-212U(N) received from the plurality of remote units204(1)-204(N) to the one or more signal sources 222(1)-222(M) as the oneor more uplink RF communications signals 224U(1)-224U(M). In thisregard, the plurality of downlink communications signals 212D(1)-212D(N)and the plurality of uplink communications signals 212U(1)-212U(N)communicated between the central unit 208 and the plurality of remoteunits 204(1)-204(N) may occupy different RF bands or channels.

In a non-limiting example, the central unit 208 may communicate thedownlink communications signal 212D(1) and the uplink communicationssignal 212U(1) with the remote unit 204(1) in the RF band 602(2) or theRF channel 604(2). The central unit 208 may communicate the downlinkcommunications signal 212D(2) and the uplink communications signal212U(2) with the remote unit 204(2) in the RF bands 602(2) and 602(M) orthe RF channels 604(2) and 604(M). The central unit 208 may communicatethe downlink communications signal 212D(N) and the uplink communicationssignal 212U(N) with the remote unit 204(N) in the RF bands 602(1) and602(M) or the RF channels 604(1) and 604(M).

To identify a remote unit among the plurality of remote units204(1)-204(N) communicating on a specific RF band, for example the RFband 602(1), among the one or more RF bands 602(1)-602(M), thecontroller 214 assigns at least one unique temporal delay pattern 206′to the RF band 602(1). The unique temporal delay pattern 206′ can be anyof the plurality of unique temporal delay patterns 206(1)-206(N) aspreviously discussed. The controller 214 may configure at least onedelay element among the plurality of delay elements 218(1)-218(N) todigitally delay at least one communications signal among the pluralityof communications signals 212(1)-212(N) based on the unique temporaldelay pattern 206′. In a non-limiting example, the controller 214 maycontrol the delay element 218(N) to digitally delay the communicationssignal 212(N) based on the unique temporal delay pattern 206′ to providea delayed communications signal 212′(N). According to previousdiscussions in FIGS. 2-5B, the determination unit 216 is able todetermine the unique temporal delay pattern 206′ associated with the RFband 602(1) in the delayed communications signal 212′(N). Thedetermination unit 216 can then identify the remote unit 204(N) amongthe plurality of remote units 204(1)-204(N) based on the determinedunique temporal delay pattern 206′.

With continuing reference to FIG. 6, to identify a remote unit among theplurality of remote units 204(1)-204(N) communicating on a specific RFchannel, for example the RF channel 604(1), among the one or more RFchannels 604(1)-604(M), the controller 214 assigns at least one uniquetemporal delay pattern 206″ to the RF channel 604(1). The uniquetemporal delay pattern 206″ can be any of the plurality of uniquetemporal delay patterns 206(1)-206(N) as previously discussed. Thecontroller 214 may configure at least one delay element among theplurality of delay elements 218(1)-218(N) to digitally delay at leastone communications signal among the plurality of communications signals212(1)-212(N) based on the unique temporal delay pattern 206′. In anon-limiting example, the controller 214 may control the delay element218(N) to digitally delay the downlink communications signal 212D(N)and/or the uplink communications signal 212U(N) based on the uniquetemporal delay pattern 206″ to provide the delayed downlinkcommunications signal 212D′(N) and/or the delayed uplink communicationssignal 212U′(N). According to previous discussions in FIGS. 2-5B, thedetermination unit 216 is able to determine the unique temporal delaypattern 206″ associated with the RF channel 604(1) in the delayeddownlink communications signal 212D′(N) and/or the delayed uplinkcommunications signal 212U′(N). The determination unit 216 can thenidentify the remote unit 204(N) among the plurality of remote units204(1)-204(N) based on the determined unique temporal delay pattern206″.

In some situations, such as receiving an E911 call from a client deviceamong the client devices 226 of FIGS. 2 and 6, it may be necessary tolocate the client device 226 in the WDS 200 of FIG. 2 and the WDS 600 ofFIG. 6 based on an identification of the client device 226. In thisregard, FIG. 7 is a flowchart of an exemplary client device locationprocess 700 for identifying a client device in the WDS 200 of FIG. 2 andthe WDS 600 of FIG. 6 based on an identification of the client device226. In a non-limiting example, location of the client device 226 may beuseful for supporting location-based services (LBS), networkoptimization, evaluation of key performance indication (KPI) statisticreport, and self-organized network (SON) operations. For the convenienceof illustration, FIG. 7 is discussed herein with reference to theplurality of uplink communications signals 212U(1)-212U(N). It shall beappreciated that the working principles discussed herein are applicableto plurality of downlink communications signals 212D(1)-212D(N) as well.

With reference to FIG. 7, the identification of the client device 226 tobe located is received by the remote unit identification system 202(block 702). In some cases, the WDSs 200 and the 600 may includehundreds of remote units 204(1)-204(N). In this regard, a binary-treesearch algorithm may be adopted to expedite the client device locationprocess 700. Accordingly, the remote unit identification system 202 maylogically organize the plurality of remote units 204(1)-204(N) into afirst remote unit group and a second remote unit group (block 704). In anon-limiting example, the first remote unit group and the second remoteunit group may include the same number of remote units if there is evennumber of remote units among the plurality of remote units204(1)-204(N). In another non-limiting example, one of the first remoteunit group and the second remote unit group may include one additionalremote unit if there is odd number of remote units among the pluralityof remote units 204(1)-204(N).

A remote group is then selected among the first remote unit group andthe second remote unit group (block 706). The controller 214 thenassigns one or more unique temporal delay patterns, which may be amongthe plurality of unique temporal delay patterns 206(1)-206(N), to theone or more remote units in the remote unit group, respectively (block708). The controller 214 then configures one or more delay elements,which may be among the plurality of the delay elements 218(1)-218(N), todigitally delay one or more uplink communications signals, which may beamong the plurality of uplink communications signals 212U(1)-212U(N),communicated by the one or more remote units in the remote unit groupbased on the one or more unique temporal delay patterns (block 710). Thedetermination unit 216 then analyzes the call report 228 to determinewhether a TA corresponding to the client device 226 changes in responseto delaying the one or more uplink communications signals based on theone or more unique temporal delay patterns (block 712).

If the TA corresponding to the client device 226 has changed, and theremote unit group includes only one remote unit, the remote unitidentification system 202 reports an identification of the remote unitin the remote unit group as the location of the client device 226 (block714) and the client device location process 700 ends. If the TAcorresponding to the client device 226 has changed, and the remote unitgroup includes more than one remote unit, the remote unit identificationsystem 202 logically organizes remote units in the remote unit groupinto the first remote unit group and the second remote unit group (block716) and returns to block 706. If the TA of the client device 226 doesnot change in delaying the one or more uplink communications signalsbased on the one or more unique temporal delay patterns, the clientdevice 226 is not associated with any remote unit in the remote unitgroup. In this case, if both of the first remote unit group and thesecond remote unit group have been searched, the client device locationprocess 700 will end. Otherwise, the client device location process 700returns to block 706.

FIG. 8 is a schematic diagram of an exemplary WDS 800 that can beconfigured to function as the WDS 200 of FIG. 2 and the WDS 600 of FIG.6. In this example, the WDS 800 is an optical fiber-based WDS. The WDS800 includes an optical fiber for distributing communications servicesfor multiple frequency bands. The WDS 800 in this example is comprisedof three main components. One or more radio interfaces provided in theform of radio interface modules (RIMs) 802(1)-802(M) are provided in acentral unit 804 to receive and process downlink electricalcommunications signals 806D(1)-806D(R) prior to optical conversion intodownlink optical fiber-based communications signals. The downlinkelectrical communications signals 806D(1)-806D(R) may be received from abase station as an example. The RIMs 802(1)-802(M) provide both downlinkand uplink interfaces for signal processing. The notations “1-R” and“1-M” indicate that any number of the referenced component, 1-R and 1-M,respectively, may be provided. The central unit 804 is configured toaccept the plurality of RIMs 802(1)-802(M) as modular components thatcan easily be installed and removed or replaced in the central unit 804.In one example, the central unit 804 is configured to support up totwelve RIMs 802(1)-802(12). Each RIM 802(1)-802(M) can be designed tosupport a particular type of radio source or range of radio sources(i.e., frequencies) to provide flexibility in configuring the centralunit 804 and the WDS 800 to support the desired radio sources.

For example, one RIM 802 may be configured to support the PersonalCommunication Services (PCS) radio band. Another RIM 802 may beconfigured to support the 800 MHz radio band. In this example, byinclusion of these RIMs 802, the central unit 804 could be configured tosupport and distribute communications signals on both PCS and LTE 700radio bands, as an example. RIMs 802 may be provided in the central unit804 that support any frequency bands desired, including but not limitedto the US Cellular band, PCS band, Advanced Wireless Services (AWS)band, 700 MHz band, Global System for Mobile communications (GSM) 900,GSM 1800, and Universal Mobile Telecommunications System (UMTS). TheRIMs 802(1)-802(M) may also be provided in the central unit 804 thatsupport any wireless technologies desired, including but not limited toCode Division Multiple Access (CDMA), CDMA200, 1×RTT, Evolution —DataOnly (EV-DO), UMTS, High-speed Packet Access (HSPA), GSM, General PacketRadio Services (GPRS), Enhanced Data GSM Environment (EDGE), TimeDivision Multiple Access (TDMA), Long Term Evolution (LTE), iDEN, andCellular Digital Packet Data (CDPD).

The RIMs 802(1)-802(M) may be provided in the central unit 804 thatsupport any frequencies desired, including but not limited to US FCC andIndustry Canada frequencies (824-849 MHz on uplink and 869-894 MHz ondownlink), US FCC and Industry Canada frequencies (1850-1915 MHz onuplink and 1930-1995 MHz on downlink), US FCC and Industry Canadafrequencies (1710-1755 MHz on uplink and 2110-2155 MHz on downlink), USFCC frequencies (698-716 MHz and 776-787 MHz on uplink and 728-746 MHzon downlink), EU R & TTE frequencies (880-915 MHz on uplink and 925-960MHz on downlink), EU R & TTE frequencies (1710-1785 MHz on uplink and1805-1880 MHz on downlink), EU R & TTE frequencies (1920-1980 MHz onuplink and 2110-2170 MHz on downlink), US FCC frequencies (806-824 MHzon uplink and 851-869 MHz on downlink), US FCC frequencies (896-901 MHzon uplink and 929-941 MHz on downlink), US FCC frequencies (793-805 MHzon uplink and 763-775 MHz on downlink), and US FCC frequencies(2495-2690 MHz on uplink and downlink).

With continuing reference to FIG. 8, the downlink electricalcommunications signals 806D(1)-806D(R) are provided to a plurality ofoptical interfaces provided in the form of optical interface modules(OIMs) 808(1)-808(N) in this embodiment to convert the downlinkelectrical communications signals 806D(1)-806D(R) into downlink opticalfiber-based communications signals 810D(1)-810D(R). The notation “1-N”indicates that any number of the referenced component 1-N may beprovided. The OIMs 808 may be configured to provide one or more opticalinterface components (OICs) that contain optical to electrical (O/E) andelectrical to optical (E/O) converters, as will be described in moredetail below. The OIMs 808 support the radio bands that can be providedby the RIMs 802, including the examples previously described above.

The OIMs 808(1)-808(N) each include E/O converters to convert thedownlink electrical communications signals 806D(1)-806D(R) into thedownlink optical fiber-based communications signals 810D(1)-810D(R). Thedownlink optical fiber-based communications signals 810D(1)-810D(R) arecommunicated over a downlink optical fiber-based communications medium812D to a plurality of remote units 814(1)-814(S), which may be remoteantenna units (“RAUs 814(1)-814(S)”). The notation “1-S” indicates thatany number of the referenced component 1-S may be provided. O/Econverters provided in the RAUs 814(1)-814(S) convert the downlinkoptical fiber-based communications signals 810D(1)-810D(R) back into thedownlink electrical communications signals 806D(1)-806D(R), which areprovided to antennas 816(1)-816(S) in the RAUs 814(1)-814(S) to clientdevices in the reception range of the antennas 816(1)-816(S).

E/O converters are also provided in the RAUs 814(1)-814(S) to convertuplink electrical communications signals 818U(1)-818U(S) received fromclient devices through the antennas 816(1)-816(S) into uplink opticalfiber-based communications signals 810U(1)-810U(S). The RAUs814(1)-814(S) communicate the uplink optical fiber-based communicationssignals 810U(1)-810U(S) over an uplink optical fiber-basedcommunications medium 812U to the OIMs 808(1)-808(N) in the central unit804. The OIMs 808(1)-808(N) include O/E converters that convert thereceived uplink optical fiber-based communications signals810U(1)-810U(S) into uplink electrical communications signals820U(1)-820U(S), which are processed by the RIMs 802(1)-802(M) andprovided as uplink electrical communications signals 820U(1)-820U(S).The central unit 804 may provide the uplink electrical communicationssignals 820U(1)-820U(S) to a base station or other communicationssystem.

Note that the downlink optical fiber-based communications medium 812Dand the uplink optical fiber-based communications medium 812U connectedto each RAU 814(1)-814(S) may be a common optical fiber-basedcommunications medium, wherein for example, wave division multiplexing(WDM) may be employed to provide the downlink optical fiber-basedcommunications signals 810D(1)-810D(R) and the uplink opticalfiber-based communications signals 810U(1)-810U(S) on the same opticalfiber-based communications medium.

The WDS 200 of FIG. 2 and the WDS 600 of FIG. 6 may be provided in anindoor environment, as illustrated in FIG. 9. FIG. 9 is a partialschematic cut-away diagram of an exemplary building infrastructure 900in which the WDS 200 of FIG. 2 and the WDS 600 of FIG. 6 can beemployed. The building infrastructure 900 in this embodiment includes afirst (ground) floor 902(1), a second floor 902(2), and a third floor902(3). The floors 902(1)-902(3) are serviced by a central unit 904 toprovide antenna coverage areas 906 in the building infrastructure 900.The central unit 904 is communicatively coupled to a base station 908 toreceive downlink communications signals 910D from the base station 908.The central unit 904 is communicatively coupled to a plurality of remoteunits 912 to distribute the downlink communications signals 910D to theplurality of remote units 912 and to receive uplink communicationssignals 910U from the plurality of remote units 912, as previouslydiscussed above. The downlink communications signals 910D and the uplinkcommunications signals 910U communicated between the central unit 904and the plurality of remote units 912 are carried over a riser cable914. The riser cable 914 may be routed through interconnect units (ICUs)916(1)-916(3) dedicated to each of the floors 902(1)-902(3) that routethe downlink communications signals 910D and the uplink communicationssignals 910U to the plurality of remote units 912 and also provide powerto the plurality of remote units 912 via array cables 918.

FIG. 10 is a schematic diagram illustrating additional details of anexemplary computer system 1000 that could be employed in the controllersdiscussed above, including, but not limited to, the remote unitidentification system 202 of FIGS. 2 and 6. As discussed above, theremote unit identification system 202 of FIG. 2 is configured touniquely identify the plurality of remote units 204(1)-204(N) in the WDS200 based on the plurality of unique temporal delay patterns206(1)-206(N). The remote unit identification system 202 of FIG. 6 isconfigured to uniquely identify at least one remote unit among theplurality of remote units 204(1)-204(N) in the WDS 600 based on at leastone unique temporal delay pattern assigned to at least one RF band or atleast one RF channel. In this regard, the computer system 1000 isadapted to execute instructions from an exemplary computer-readablemedium to perform these and/or any of the functions or processingdescribed herein.

With reference to FIG. 10, the computer system 1000 may include a set ofinstructions that may be executed to uniquely identify the plurality ofremote units 204(1)-204(N) in the WDSs 200 and 600. The computer system1000 may be connected (e.g., networked) to other machines in a LAN, anintranet, an extranet, or the Internet. While only a single device isillustrated, the term “device” shall also be taken to include anycollection of devices that individually or jointly execute a set (ormultiple sets) of instructions to perform any one or more of themethodologies discussed herein. The computer system 1000 may be acircuit or circuits included in an electronic board card, such as aprinted circuit board (PCB), a server, a personal computer, a desktopcomputer, a laptop computer, a personal digital assistant (PDA), acomputing pad, a mobile device, or any other device, and may represent,for example, a server or a user's computer.

The computer system 1000 in this embodiment includes a processingcircuit (“processor 1002”), a main memory 1004 (e.g., read-only memory(ROM), flash memory, dynamic random access memory (DRAM), such assynchronous DRAM (SDRAM), etc.), and a static memory 1006 (e.g., flashmemory, static random access memory (SRAM), etc.), which may communicatewith each other via a data bus 1008. Alternatively, the processor 1002may be connected to the main memory 1004 and/or the static memory 1006directly or via some other connectivity bus or connection. The mainmemory 1004 and the static memory 1006 may be any type of memory.

The processor 1002 may be a microprocessor, central processing unit, orthe like. More particularly, the processor 1002 may be a complexinstruction set computing (CISC) microprocessor, a reduced instructionset computing (RISC) microprocessor, a very long instruction word (VLIW)microprocessor, a processor implementing other instruction sets, orother processors implementing a combination of instruction sets. Theprocessor 1002 is configured to execute processing logic in instructionsfor performing the operations and steps discussed herein.

The computer system 1000 may further include a network interface device1010. The computer system 1000 also may or may not include an input1012, configured to receive input and selections to be communicated tothe computer system 1000 when executing instructions. The computersystem 1000 also may or may not include an output 1014, including, butnot limited to, a display, a video display unit (e.g., a liquid crystaldisplay (LCD) or a cathode ray tube (CRT)), an alphanumeric input device(e.g., a keyboard), and/or a cursor control device (e.g., a mouse).

The computer system 1000 may or may not include a data storage devicethat includes instructions 1016 stored in a computer-readable medium1018. The instructions 1016 may also reside, completely or at leastpartially, within the main memory 1004 and/or within the processor 1002during execution thereof by the computer system 1000, the main memory1004 and the processor 1002 also constituting the computer-readablemedium 1018. The instructions 1016 may further be transmitted orreceived over a network 1020 via the network interface device 1010.

While the computer-readable medium 1018 is shown in an exemplaryembodiment to be a single medium, the term “computer-readable medium”should be taken to include a single medium or multiple mediums (e.g., acentralized or distributed database, and/or associated caches andservers) that store the one or more sets of instructions. The term“computer-readable medium” shall also include any medium that is capableof storing, encoding, or carrying a set of instructions for execution bythe processing device and that cause the processing device to performany one or more of the methodologies of the embodiments disclosedherein. The term “computer-readable medium” shall accordingly include,but not be limited to, solid-state memories, optical mediums, andmagnetic mediums.

The embodiments disclosed herein include various steps. The steps of theembodiments disclosed herein may be formed by hardware components or maybe embodied in machine-executable instructions, which may be used tocause a general-purpose or special-purpose processor programmed with theinstructions to perform the steps. Alternatively, the steps may beperformed by a combination of hardware and software.

The embodiments disclosed herein may be provided as a computer programproduct, or software, that may include a machine-readable medium (orcomputer-readable medium) having stored thereon instructions, which maybe used to program a computer system (or other electronic devices) toperform a process according to the embodiments disclosed herein. Amachine-readable medium includes any mechanism for storing ortransmitting information in a form readable by a machine (e.g., acomputer). For example, a machine-readable medium includes: amachine-readable storage medium (e.g., ROM, random access memory(“RAM”), a magnetic disk storage medium, an optical storage medium,flash memory devices, etc.), and the like.

Unless otherwise expressly stated, it is in no way intended that anymethod set forth herein be construed as requiring that its steps beperformed in a specific order. Accordingly, where a method claim doesnot actually recite an order to be followed by its steps, or it is nototherwise specifically stated in the claims or descriptions that thesteps are to be limited to a specific order, it is in no way intendedthat any particular order be inferred.

Various modifications and variations can be made without departing fromthe spirit or scope of the invention. Since modifications, combinations,sub-combinations and variations of the disclosed embodimentsincorporating the spirit and substance of the invention may occur topersons skilled in the art, the invention should be construed to includeeverything within the scope of the appended claims and theirequivalents.

What is claimed is:
 1. A wireless distribution system (WDS), comprising:a plurality of signal paths; a plurality of remote units, each remoteunit among the plurality of remote units communicatively coupled to arespective signal path among the plurality of signal paths; a centralunit configured to communicate a respective communications signal amonga plurality of communications signals to each remote unit among theplurality of remote units in the respective signal path communicativelycoupled to the remote unit; a plurality of delay elements disposed inthe plurality of signal paths, respectively, wherein each delay elementamong the plurality of delay elements is configured to digitally delaythe respective communications signal communicated in the respectivesignal path according to a respective unique temporal delay patternamong a plurality of unique temporal delay patterns assigned to arespective remote unit among the plurality of remote unitscommunicatively coupled to the respective signal path to provide adelayed communications signal in the respective signal path; and aremote unit identification system, comprising: a controller configuredto assign the plurality of unique temporal delay patterns to theplurality of remote units in the WDS; and a determination unitconfigured to: for at least one delayed communications signal providedin at least one signal path among the plurality of signal paths:determine a unique temporal delay pattern associated with the at leastone delayed communications signal; and identify a remote unit among theplurality of remote units communicatively coupled to the at least onesignal path based on the unique temporal delay pattern.
 2. The WDS ofclaim 1, further comprising a plurality of uplink signal paths, wherein:each remote unit among the plurality of remote units is communicativelycoupled to a respective uplink signal path among the plurality of uplinksignal paths; the central unit is further configured to receive arespective uplink communications signal among a plurality of uplinkcommunications signals from each remote unit among the plurality ofremote units in the respective uplink signal path communicativelycoupled to the remote unit; each delay element among the plurality ofdelay elements is further configured to digitally delay the respectiveuplink communications signal communicated in the respective uplinksignal path according to the unique temporal delay pattern assigned tothe respective remote unit communicatively coupled to the respectiveuplink signal path to provide a delayed uplink communications signal inthe respective uplink signal path; and the determination unit is furtherconfigured to: for at least one delayed uplink communications signalprovided in at least one uplink signal path among the plurality ofuplink signal paths: determine a unique temporal delay patternassociated with the at least one delayed uplink communications signal;and identify a remote unit among the plurality of remote unitscommunicatively coupled to the at least one uplink signal path based onthe unique temporal delay pattern.
 3. The WDS of claim 1, furthercomprising a plurality of downlink signal paths, wherein: each remoteunit among the plurality of remote units is communicatively coupled to arespective downlink signal path among the plurality of downlink signalpaths; the central unit is further configured to communicate arespective downlink communications signal among a plurality of downlinkcommunications signals to each remote unit among the plurality of remoteunits over the respective downlink signal path communicatively coupledto the remote unit; each delay element among the plurality of delayelements is further configured to digitally delay the respectivedownlink communications signal communicated in the respective downlinksignal path according to the unique temporal delay pattern assigned tothe respective remote unit communicatively coupled to the respectivedownlink signal path to provide a delayed downlink communications signalin the respective downlink signal path; and the determination unit isfurther configured to: for at least one delayed downlink communicationssignal provided in at least one downlink signal path among the pluralityof downlink signal paths: determine a unique temporal delay patternassociated with the at least one delayed downlink communications signal;and identify a remote unit among the plurality of remote unitscommunicatively coupled to the at least one downlink signal path basedon the unique temporal delay pattern.
 4. The WDS of claim 1, furthercomprising a plurality of downlink signal paths and a plurality ofuplink signal paths, wherein: each remote unit among the plurality ofremote units is communicatively coupled to a respective downlink signalpath among the plurality of downlink signal paths and a respectiveuplink signal path among the plurality of uplink signal paths; thecentral unit is further configured to: communicate a respective downlinkcommunications signal among a plurality of downlink communicationssignals with each remote unit among the plurality of remote units in therespective downlink signal path communicatively coupled to the remoteunit; and communicate a respective uplink communications signal among aplurality of uplink communications signals with each remote unit amongthe plurality of remote units in the respective uplink signal pathcommunicatively coupled to the remote unit; and each delay element amongthe plurality of delay elements is further configured to: digitallydelay the respective downlink communications signal communicated in therespective downlink signal path according to the unique temporal delaypattern assigned to the respective remote unit communicatively coupledto the respective downlink signal path to provide a delayed downlinkcommunications signal in the respective downlink signal path; anddigitally delay the respective uplink communications signal communicatedin the respective uplink signal path according to the unique temporaldelay pattern assigned to the respective remote unit communicativelycoupled to the respective uplink signal path to provide a delayed uplinkcommunications signal in the respective uplink signal path; and thedetermination unit is further configured to: for at least one delayeddownlink communications signal provided in at least one downlink signalpath among the plurality of downlink signal paths and at least onedelayed uplink communications signal provided in at least one uplinksignal path among the plurality of uplink signal paths: determine aunique temporal delay pattern associated with the at least one delayeddownlink communications signal and the at least one delayed uplinkcommunications signal; and identify a remote unit among the plurality ofremote units communicatively coupled to the at least one downlink signalpath and the at least one uplink signal path based on the uniquetemporal delay pattern.
 5. The WDS of claim 1, wherein: each uniquetemporal delay pattern among the plurality of unique temporal delaypatterns comprises a plurality of temporal delay periods correspondingto a plurality of temporal delay values, respectively; and a sequence ofthe plurality of temporal delay values makes each unique temporal delaypattern among the plurality of unique temporal delay patterns uniquelydistinguishable from rest of the plurality of unique temporal delaypatterns.
 6. The WDS of claim 5, wherein each of the plurality oftemporal delay values in each of the plurality of unique temporal delaypatterns is a multiple of a predefined temporal unit (TU).
 7. The WDS ofclaim 5, wherein each delay element among the plurality of delayelements is configured to digitally delay the communications signalcommunicated in the respective signal path for the plurality of temporaldelay values in the plurality of temporal delay periods associated withthe respective unique temporal delay pattern, respectively, to providethe respective communications signal.
 8. The WDS of claim 5, wherein thedetermination unit is further configured to determine the uniquetemporal delay pattern associated with the at least one delayedcommunications signal based on the plurality of temporal delay valuesassociated with the at least one delayed communications signal in theplurality of temporal delay periods, respectively.
 9. The WDS of claim1, wherein: the central unit is communicatively coupled to one or moresignal sources configured to communicate one or more radio frequency(RF) communications signals associated with one or more RF bands; thecentral unit is further configured to communicate the one or more RFcommunications signals as the plurality of communications signals overthe plurality of signal paths; the controller is further configured toassign at least one unique temporal delay pattern to at least one RFband among the one or more RF bands associated with at least onecommunications signal among the plurality of communications signals; atleast one delay element among the plurality of delay elements is furtherconfigured to digitally delay the at least one communications signalbased on the at least one unique temporal delay pattern to provide theat least one delayed communications signal in the at least one signalpath among the plurality of signal paths; and the determination unit isfurther configured to: determine the at least one unique temporal delaypattern associated with the at least one RF band in the at least onedelayed communications signal in the at least one signal path; andidentify at least one remote unit among the plurality of remote unitscommunicatively coupled to the at least one signal path based on the atleast one unique temporal delay pattern.
 10. The WDS of claim 1, whereinthe controller is further configured to programmably control each of theplurality of delay elements to digitally delay the respectivecommunications signal according to the unique temporal delay patternassigned to the respective remote unit to provide the delayedcommunications signal in the respective signal path.
 11. The WDS ofclaim 1, wherein the central unit comprises: a plurality ofelectrical-to-optical (E/O) converters configured to convert a pluralityof downlink communications signals into downlink optical fiber-basedcommunications signals for communication to the plurality of remoteunits over a downlink optical fiber-based communications medium; and aplurality of optical-to-electrical (O/E) converters configured toconvert uplink optical fiber-based communications signals received fromthe plurality of remote units over an uplink optical fiber-basedcommunications medium into a plurality of uplink communications signals.12. The WDS of claim 1, wherein the determination unit is furtherconfigured to determine a location of the identified remote unit. 13.The WDS of claim 12, wherein the determination unit is furtherconfigured to determine the location of the identified remote unit basedon a predefined physical location associated with identified the remoteunit.
 14. The WDS of claim 12, wherein the determination unit is furtherconfigured to determine a location of a client device communicating therespective communications signal to the identified remote unit based onthe location of the identified remote unit.
 15. The WDS of claim 14,wherein the remote unit identification system is further configured to:receive an identification of the client device; logically organize theplurality of remote units in the WDS into a first remote unit group anda second remote unit group; for each remote unit group among the firstremote unit group and the second remote unit group: assign one or moreunique temporal delay patterns to one or more remote units in the remoteunit group, respectively; control one or more delay elements among theplurality of delay elements to delay one or more uplink communicationssignals communicated by the one or more remote units in the remote unitgroup based on the one or more unique temporal delay patterns,respectively; analyze a call report to determine whether a timingadvance (TA) corresponding to the client device changes in response todelaying the one or more uplink communications signals based on the oneor more unique temporal delay patterns; and if the TA of the clientdevice has changed: if the remote unit group comprises only one remoteunit, report the identification of the remote unit in the remote unitgroup; and if the remote unit group comprises more than one remote unit,logically organize the remote units in the remote unit group into thefirst remote unit group and the second remote unit group.
 16. A methodfor identifying a client device in a wireless distribution system (WDS),comprising: receiving an identification of the client device; logicallyorganizing a plurality of remote units in the WDS into a first remoteunit group and a second remote unit group; and for each remote unitgroup among the first remote unit group and the second remote unitgroup: assigning one or more unique temporal delay patterns to one ormore remote units in the remote unit group, respectively; delaying oneor more communications signals communicated with the one or more remoteunits in the remote unit group based on the one or more unique temporaldelay patterns, respectively; analyzing a call report to determinewhether a timing advance (TA) corresponding to the client device changesin response to delaying the one or more communications signals based onthe one or more unique temporal delay patterns; and if the TA of theclient device has changed: if the remote unit group comprises only oneremote unit, reporting an identification of the remote unit in theremote unit group; and if the remote unit group comprises more than oneremote unit, logically organizing the remote units in the remote unitgroup into the first remote unit group and the second remote unit group.17. The method of claim 16, further comprising determining a location ofthe reported remote unit.
 18. The method of claim 17, further comprisingdetermining the location of the reported remote unit based on apredefined physical location associated with reported the remote unit.19. The method of claim 17, further comprising determining a location ofthe client device based on the determined location of the reportedremote unit.